lipases Flashcards
(9 cards)
What do lipase enzymes catalyse?
The hydrolysis of triglycerides to yield free fatty acids
Lipase enzymes are plentiful in malt acrospires.
Which other enzymes are involved in the breakdown of triglycerides?
Esterase enzymes
Esterases also play a role in the hydrolysis of triglycerides.
Why are free fatty acids more soluble in wort than triglycerides?
They are readily oxidised, making them more polar and hence even more soluble
Oxidation increases the solubility of free fatty acids.
What do lipoxygenases (LOX) catalyse?
The oxidation of fatty acids to produce hydroxy and hydroperoxyl fatty acids
Lipoxygenases are important in the brewing process.
How many lipoxygenases are found in barley?
Two, called LOX-1 and LOX-2
Both lipoxygenases have different heat stability characteristics.
Which lipoxygenase is more heat labile?
LOX-2
LOX-2 is denatured during kilning, leaving LOX-1 active in mashing.
What enhances the activity of LOX-1?
A more heat stable enzyme related to peroxygenase
This enhancement occurs during the mashing process.
Why is the oxidation of unsaturated fatty acids to aldehydes important?
They are major contributors to stale beer flavour
The oxidation reactions are complex and can affect beer quality.
What can help reduce the concentration of aldehyde precursors?
Minimising oxygen pick up and the action of LOX in the mash with low pH and high mashing temperature
These factors can improve flavour stability.
